JAMA takes on the dietary supplement industry. The unregulated $30 billion industry is likely not pleased with their conclusions. - D

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"Most randomized clinical trials of vitamin and mineral supplements have not demonstrated clear benefits for primary or secondary prevention of chronic diseases not related to nutritional deficiency. Indeed, some trials suggest that micronutrient supplementation in amounts that exceed the recommended dietary allowance (RDA) ... may have harmful effects."

Dietary supplements encompass a wide variety of products from vitamins, minerals, and botanicals to probiotics, protein powders, and fish oils. During the past 2 decades, a steady stream of high-quality studies evaluating dietary supplements has yielded predominantly disappointing results about potential health benefits, whereas evidence of harm has continued to accumulate. How consumers have responded to these scientific developments is not known. In this issue of JAMA, the report by Kantor and colleagues sheds light on this important question.